Elevator heat treatment furnace construction



Oct. 7, 1958 w. R. GILBERT ELEVATOR HEATQTREATME'NT FURNACE CONSTRUCTION Filed March 15 mmvroa ii.

fizz United St s Patent ,fiiice ELEVATOR HEAT TREATMENT FURNACE CONSTRUCTION Application March 15, 1955, Serial No. 494,399 3 Claims. (Cl. 263-46) The present invention relates to the heat treatment art, and has particular reference to a novel type of furnace for heat treating metal articles of substantial height.

The presently utilized horizontal type of heat treatment furnaces permit the entry and the exit of metal objects of extended length, but find it impractical to heat treat objects of extended height, such as airplane, ship or machine element parts which are up to seven or eight feet in height. Moreover, the installation'of a horizontal type furnace of sufiicient height has a substantial disadvantage in that the heat enveloping atmosphere is lost when the furnace door or doors are opened for inlet and exit of the work.

The principal object of the invention is to provide a novel furnace construction particularly suitable for the heat treatment of large metal articles.

Another object of the invention is to provide a novel furnace construction for the heat treatment of large metal articles in a hydrogen or a hydrogen containing atmosphere which is kept free from contamination and free from explosion hazard and loss of atmosphere during input and exit of work.

Still another object is to provide a novel elevator type heat treatment furnace in which the heat treatment and the cooling chambers are in superimposed vertical relation.

With the above and other objects and advantageous features which will become apparent as the description proceeds, the invention consists of a novel arrangement of parts more fully disclosed in the detailed description thereof, in conjunction with the accompanying drawings, and more specifically defined in the claims appended there- 10.

The drawing discloses a preferred furnace construction showing in superimposed vertical relation a heat treatment chamber, a cooling chamber, and a work loading and unloading chamber, for the bright annealing of stainless steel and similar metal articles of substantial height.

In the bright annealing of stainless and other steels and other metals at elevated temperatures such as 2100 degrees F., it is preferred to utilize a heat treatment atmosphere of hydrogen or containing hydrogen, and to control flow of the heat treatment atmosphere through the heat treatment chamber at a rate which eliminates contaminated atmospheres resulting from introduction of the work undergoing heat treatment; contamination from the refractories of the heat treatment chamber is preferably avoided by using a gas tight metal liner. The hydrogen or hydrogen containing atmosphere, however, is explosive when mixed with the proper proportion of air at high temperatures, and it is therefore necessary to cool the outflowing heat treatment atmosphere; the volume is flow controlled to maintain a proper heat treatment atmosphere without waste.

To this end, I have devised a heat treatment furnace of vertical type, with a lower chamber. for loading and unloading the work, a superimposed cooling chamber with closure doors, a superimposed heat treatment chamber Patented Oct. 7, 1958 by a metal article to be heat treated is loaded on an elevator platform in the lower chamber, and elevated through the cooling chamber and into the heat treatment chamber; after being heat treated, the article is lowered into the cooling chamber, and after cooling is then lowered to the lower chamber for unloading. The heat treatment atmosphere is admitted into the heat treatment chamber through a standard type inlet or injector, and slowly seeps down through the cooling chamber to the lower chamber to escape to atmosphere; the work movement is preferably by hydraulic elevator.

Referring to the drawing, the elevator type heat treatment furnace 10 is housed in a supporting frame 11 seated on a floor 12, and includes an upper heat treatment chamber 13 which may be of any desired width, and preferably is of square cross section, and is of ample height to accept entry of large metal articles through a lower opening 14, which as illustrated is slightly constricted to provide a throat 15.

Positioned directly below the heat treatment chamber 13 is a cooling chamber 16, which is provided with suit able cooling fluid flow passages in the walls 17thereof. A loading and unloading chamber 18 is positioned directly below the cooling chamber, and is preferably wall enclosed, as indicated by the reference numberal 19, and with a door 20, whereby the work may be shifted in and out.

The wall enclosure 19 is preferably of metal, and lines the inner wall 21 of the cooling chamber, the throat 15, and the heat treatment chamber to provide an extended vertical gas tight passageway 22 for an elevator 22a which has a lift cylinder 23 slidable through a suitable pit 24 in the floor and through a downwardly extending casing 25, the cylinder'23 having side guides 26 slidably mounted on guide rods 27 which extend upwardly to at least the floor of the cooling chamber, as it has been found diflicult to provide a free lift without guides for a height greater than nine feet. The upper position of lift cylinder 23 is preferably hollow, to permit flow of cooling fluid therethrough through an inlet 28 and an outlet 29.

The lower portion tending upwardly within the frame 11. The upper portion of the cooling chamber is provided with similarly operable doors 36, 37, slidably positioned in recesses 38, 39.

Heat treatment atmosphere of predetermined proportioned chemical composition and suitable for the work being heat treated and the particular heat treatment desired is introduced into the heating chamber in any suitable manner, as by pressure injectors 40, to keep the heating chamber filled while seeping down slowly through the cooling chamber and into the lower floor level chamber and out to atmosphere. The preferred heat treatment atmosphere for the bright annealing of stainless steel is hydrogen; since the hydrogen is light, it slowly seeps down through the cooling chamber and is cooled below the ignition point when it enters the lower chamber and passes out to atmosphere.

The operation of the novel furnace may now be explained. Work being deposited on the elevator, the lower closure doors and the upper closure doors are opened, and the elevator lifts the work into the heat treatment It is preferred to utilize the elevator base, which is made of suitable heat resistant material, as a closure for the heat treatment chamber during the heat treatment. During this operation, it may be preferred to close the doors 35, 36 and 32, 33 to prevent excessive seepage of the heat treatment atmosphere, in such case the doors are preferably arcuately slotted to fit snugly around the elevator shaft. The heat treatment being completed, the work is lowered to the cooling chamber,

the upper closure doors being opened for the transfer and then closed; after cooling, the lower doors are opened and the work is lowered to the floor. The lower closure doors being closed, the work is removed, and the operation is repeated.

Although I have disclosed a specific embodiment of my invention, changes in the size, shape and arrangement of the parts may be made to meet different requirements for vertical type heat treating furnaces, without departing from the spirit or the scope of the invention as defined in the appended claims.

I claim:

1. A vertical type furnace for heat treating metal Work in a hydrogen atmosphere or the like, said furnace having a work loading and unloading chamber, a cooling chamber positioned above the loading and unloading chamber, a heat treatment chamber positioned above the cooling chamber and having a throat portion interconnecting same, a vertical passageway from the loading and unloading chamber extending upwardly through the cooling chamber to said throat, an elevator having a work receiving platform mounted to pass through said passageway and inlet means for admitting heat treatment atmosphere directly to said heat treatment chamber under pressure, said heat treatment chamber, said throat portion, and said cooling chamber having a continuous metal liner, said liner being imperforate with the exception of said atmosphere inlet means, whereby a continuous flow of heat treatment atmosphere through said inlet means will cause said atmosphere to eventually descend through said throat portion and said cooling chamber before mixing with the surrounding atmosphere.

2. In the structure of claim 1, said cooling chamber having openable closure means at the upper and lower portions thereof.

3. In the structure of claim 1, said elevator having a shaft, at least the upper portion of said shaft being water cooled.

References Cited in the file of this patent UNITED STATES PATENTS 

